1. Field of the Invention
The present invention relates to a method for drying a wafer and an apparatus for performing the same. More particularly, the present invention relates to a method for drying a wafer after a rinsing operation by instantaneously reducing the pressure in a drying chamber in order to dry a wafer without forming watermarks and an apparatus for performing the method.
2. Description of the Related Art
In semiconductor manufacturing technology, particles transcribed on a wafer or impurities remaining on a wafer are generally removed from the wafer by rinsing the wafer with chemicals during a wet rinsing process and then drying the wafer. Alternatively, particles or impurities may be conventionally removed from a wafer by applying deionized water onto the wafer using an ultrasonic wave or a brush while rotating the wafer.
After the wafer is rinsed with the deionized water, the wafer is dried using a spin drying process, an isopropyl alcohol (IPA) vapor drying process, or a Marangoni drying process in order to remove the deionized water remaining on the wafer.
In a spin drying process, water particles on a wafer are expelled from the wafer due to a rotational force resulting from the wafer being rotated at a high speed. In an IPA vapor drying process, IPA vapor at a high temperature is applied to the wafer loaded in a sealed drying chamber, and then the water particles on the wafer are substituted with the IPA and then the IPA on the wafer is naturally removed from the wafer. In a Marangoni drying process, water particles remaining on a wafer are removed due to the Marangoni force while the wafer immersed in deionized water is lifted into an atmosphere including IPA and water particles are slowly drained from the wafer exposed to an atmosphere including IPA.
The above-mentioned conventional drying processes, however, have several disadvantages. As for the spin drying process, watermarks may be generated on a film surface simultaneously having hydrophobicity and hydrophilicity characteristics and main patterns of the film may not be completely dried even though the wafer has been through the spin drying process. Additionally, in a memory device having a storage node polysilicon structure, such as DRAM device, storage polysilicon films may be attached to each other due to the surface tension of the water on the wafer.
During an IPA vapor drying process, a defect such as the formation of gels may occur on the wafer or storage polysilicon films may be cohered to each other.
Furthermore, in a Marangoni drying process, the time for drying the wafer is too long, and storage polysilicon films may be also cohered to each other when the drying process is not precisely executed under exact processing conditions.
One common disadvantage of these conventional drying processes is that particles remaining on the wafer may not be completely removed from the wafer during the drying processes. On the other hand, other particles may be newly formed on the wafer during the drying processes in addition to the presence of the previously remaining particle. In addition, if isopropyl alcohol is used in the drying of the wafer, a carbon environmental pollution may occur in the isopropyl alcohol.